Avian pathogenic Escherichia coli (APEC) is the responsible pathogen for colibacillosis in poultry, and is a potential gene source for human extraintestinal pathogenic Escherichia coli. Escherichia coli type III secretion system 2 (ETT2) is widely distributed in human and animal ExPEC isolates, and is crucial for the virulence of ExPEC. Transcriptional regulator YgeK, located in the ETT2 gene cluster, was identified as an important regulator of gene expression in enterohemorrhagic E. coli (EHEC). However, the role of YgeK in APEC has not been reported. In this study, we performed amino acid alignment analysis of YgeK among different E. coli strains and generated ygeK mutant strain AE81ΔygeK from clinical APEC strain AE81. Flagellar formation, bacterial motility, serum sensitivity, adhesion, and virulence were all significantly reduced following the inactivation of YgeK in APEC. Then, we performed transcriptome sequencing to analyze the functional pathways involved in the biological processes. Results suggested that ETT2 transcriptional regulator YgeK plays a crucial role in APEC virulence. These findings thus contribute to our understanding of the function of the ETT2 cluster, and clarify the pathogenic mechanism of APEC.

Avian pathogenic Escherichia coli (APEC), a subgroup of extraintestinal pathogenic E. coli (ExPEC), causes infections in poultry and may pose a public health risk. Although previous reviews have examined the epidemiology, genotypes, pathogenicity, antimicrobial resistance, and zoonotic risk of APEC, its global research landscape and development trends have not been systematically evaluated. This study analyzed 1121 APEC-related publications published from 2000 to 2025 and indexed in the Web of Science Core Collection (WoSCC). Bibliometrix, VOSviewer, and CiteSpace were used to examine publication trends, countries, institutions, journals, citations, and keywords. The number of publications increased steadily, with more rapid growth after 2019. China produced the most publications, whereas the USA received the most citations. Iowa State University, Yangzhou University, and Anhui Agricultural University were the leading institutions, and Poultry Science, Veterinary Microbiology, and Avian Diseases were the most productive journals. Keyword co-occurrence, clustering, and burst analyses identified infection mechanisms, molecular identification, antimicrobial resistance, and immune responses as the main research topics. These findings provide an overview of the development of APEC research and may support future studies on broad-spectrum vaccines, phage therapy, and microbiota-based interventions for APEC prevention and control.